This is going to be a controversial post. I'll get that out of the way up front.
OSR, or "Old School Rennaissance" is a newish trend (ironically) in roleplaying games that's quite the rage in certain circles on the Internet these days. The OGL (Open Game License) enabled it; after running under the OGL for some time, someone got the bright idea of "reverse engineering" Advanced Dungeons & Dragons (first edition) out of the open content. The result was OSRIC, (Old School Reference & Index Compendium). OSRIC is basically 1e, but open. Because of it, anyone could publish material compatible for 1e by making it compatible with OSRIC.
Prior to OSRIC, there were other games that had a bit of "Old School" flavor under the OGL; Castles & Crusades, for example, was a kind of hybrid of some older rulesets and the 3e SRD. But for my purposes, the "OSR" really starts with OSRIC. Because the OGC is utilized to make a "clone" if you will of the older ruleset, OSRIC is often called the first "retro-clone." For a time, it was questionable whether or not what OSRIC attempted to do was legal, but after it became apparent that they were in the clear, other retro-clones popped up on the marketplace. Basic Fantasy Roleplaying Game and Labyrinth Lord are both slightly different takes on the Moldvay B/X ruleset. Swords & Wizardry is an attempt to retroclone the original D&D ruleset; before the bifurcation into AD&D and B/XD&D even happened. Because of broad similarities in the rules of all those original rulesets, material for one is mostly compatible with material for the other, and elements can kinda be mixed and matched as desired.
The interesting thing about this is that some other publishers have since put out material that's compatible with these products. OSRIC compatible modules. S&W compatible settings. Etc. There's even several magazines that are kinda like very old school Dragon magazines in some ways; dedicated to promoting these old school games and products.
Now; it's probably obvious from many posts in the past on this topic; I'm not really all that keen on playing any of these games myself. I don't like old school D&D. I left old school D&D for greener pastures and only the "modernization" of the rules that happened at 3e tempted me back. Since then, I've made RPGs one of my main hobbies again, and D&D is the game I play most often. 3e+, that is.
However, I have a keen interest in the development of the OSR, since with the advent of 4e, I'm kinda in a similar situation; looking for material that's compatible with an out of print version of the game. And sadly, this is where my problems with the OSR start. It's not with the idea of it, which I actually quite like. It's with some of the personalities associated with it. I've read a lot of OSR blogs, I've seen a lot of posts from OSR fans on places like ENWorld and even Circvs Maximvs, and frankly, these guys are a bunch of jerks more often than not.
Now, I get that a few loudmouths can spoil the fun for everyone. Most OSR players and fans are probably fine people. But a lot of the vocal ones, have a real problem. There's a strong vibe in OSR themed discussions online of smugness and fundamentalism. They reject anything that postdates the early 80s as wrong, mistaken, foolish, and occasionally treat it as if it's heretical. They're an insular, clannish group that is not interested in reaching out to the broader RPG fan community, and in fact often doesn't acknowledge their existance, other than with a teeth-gritting railing against them for somehow "ruining" the hobby.
I've been somewhat appalled to see otherwise even the reasonable and polite OSRers frequently make allusions to trying to recreate a "pure" Gygaxian playstyle; doing things for no other reason than because they believe that's how Gary did it. Gary was not a prophet, and the first edition D&D was not holy writ. There's nothing wrong with liking what you like (and not what you don't) but the outright dismissive and often contemptuous treatment of any other roleplaying paradigm or ruleset is a real turnoff at times.
Anyway, I guess my point is that my academic interest in the OSR movement has been considerably blunted by many of the people who are part of it, which is a real shame. It doesn't invalidate the movement for those who like it, nor is it meant to be a condemnation of those people who are merely enthusiastic for out of print games without being insulting, but sadly, I've found that sifting the wheat from the chaff in this regard isn't worth the effort to me personally.
If the OSR truly is interested in recruiting into their ranks, expanding their movement, and otherwise contributing meaningful to the hobby (which, honestly, I'm not sure if they do want that, or even if they should care) then they need to present a more accomodating front. The smug, self-satisfied, and dismissive tone of too many of the OSR people that I've encountered online has ensured that I will never develop enough curiousity to try out one of these games. Not even for a mere nostalgic temporary thrill-ride.